To complete a well, one or more sets of perforations may be created downhole using perforating guns. Such perforations allow fluid from producing zones to flow into the wellbore for production to the surface. To create perforations in multiple reservoirs or in multiple sections of a reservoir, multi-gun strings are typically used. A multi-gun string may be lowered to a first position to fire a first gun or bank of guns, then moved to a second position to fire a second gun or bank of guns, and so forth.
Selectable switches are used to control the firing sequence of the guns in the string. Simple devices include dual diode switches for two-gun systems and percussion actuated mechanical switches or contacts for multi-gun systems. A percussion actuated mechanical switch is activated by the force from a detonation. Guns are sequentially armed starting from the lowest gun, using the force of the detonation to set a switch to complete the circuit to the gun above and to break connection to the gun below. The switches are used to step through the guns or charges from the bottom up to select which gun or charge to fire. Some systems allow certain of the switches to be bypassed if failure occurs.
Other operations can also be performed in a well with other types of tools. As tools become more technologically sophisticated, electronic components are added. To date, however, a convenient and flexible device has conventionally not been provided to communicate with or to test the various types of tools.